Fluid infusion device

ABSTRACT

A fluid infusion device is provided with a cannula spring which functions as an introducer needle, a retraction return spring, and a fluid path. A hollow cannula tubing is wound, bent and sharpened into a shape which allows it to operate as an introducer needle, retraction spring and fluid path in an infusion device. A button is used to insert the introducer needle portion of the cannula spring and a soft catheter, and once the introducer needle portion and catheter have been fully inserted, an engagement between the button and post of the base of the infusion device releases the cannula spring such that the introducer needle portion of the cannula spring automatically retracts, leaving the catheter in the body. An end of the introducer needle portion of the cannula spring remains in fluid communication with the catheter in the body to provide an uninterrupted fluid path.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Application No. 61/983,972, filed on Apr. 24, 2014 in theU.S. Patent and Trademark Office, the contents of which are incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates generally to medical infusion systems,such as a fluid infusion device, where a piece of hollow cannula tubingis wound, bent and sharpened into a shape which allows it to operate asan introducer needle, retraction spring and fluid path in an infusiondevice. A button of the infusion device is used to insert the introducerneedle portion of the cannula spring and a soft catheter, and once theintroducer needle portion and catheter have been fully inserted, anengagement releases the cannula spring such that the introducer needleportion of the cannula spring automatically retracts, leaving thecatheter in the body of the user. An end of the introducer needleportion of the cannula spring remains in the inserted catheter toprovide an uninterrupted fluid path.

BACKGROUND OF THE INVENTION

Diabetes is a group of diseases characterized by high levels of bloodglucose resulting from the inability of diabetic patients to maintainproper levels of insulin production when required. Persons with diabeteswill require some form of daily insulin therapy to maintain control oftheir glucose levels. Diabetes can be dangerous to the affected patientif it is not treated, and it can lead to serious health complicationsand premature death. However, such complications can be minimized byutilizing one or more treatment options to help control the diabetes andreduce the risk of complications.

The treatment options for diabetic patients include specialized diets,oral medications and/or insulin therapy. The main goal of diabetestreatment is to control the diabetic patient's blood glucose or sugarlevel. However, maintaining proper diabetes management may becomplicated because it has to be balanced with the activities of thediabetic patient.

For the treatment of type 1 diabetes, there are two principal methods ofdaily insulin therapy. In the first method, diabetic patients usesyringes or insulin pens to self-inject insulin when needed. This methodrequires a needle stick for each injection, and the diabetic patient mayrequire three to four injections daily. The syringes and insulin pensthat are used to inject insulin are relatively simple to use and costeffective.

Another effective method for insulin therapy and managing diabetes isinfusion therapy or infusion pump therapy in which an insulin pump isused. The insulin pump can provide continuous infusion of insulin to adiabetic patient at varying rates in order to more closely match thefunctions and behavior of a properly operating pancreas of anon-diabetic person that produces the required insulin, and the insulinpump can help the diabetic patient maintain his/her blood glucose levelwithin target ranges based on the diabetic patient's individual needs.

Infusion pump therapy requires an infusion cannula, typically in theform of an infusion needle or a flexible catheter, that pierces thediabetic patient's skin and through which, infusion of insulin takesplace. Infusion pump therapy offers the advantages of continuousinfusion of insulin, precision dosing, and programmable deliveryschedules.

In infusion therapy, insulin doses are typically administered at a basalrate and in a bolus dose. When insulin is administered at a basal rate,insulin is delivered continuously over 24 hours in order to maintain thediabetic patient's blood glucose levels in a consistent range betweenmeals and rest, typically at nighttime. Insulin pumps may also becapable of programming the basal rate of insulin to vary according tothe different times of the day and night. In contrast, a bolus dose istypically administered when a diabetic patient consumes a meal, andgenerally provides a single additional insulin injection to balance theconsumed carbohydrates. Insulin pumps may be configured to enable thediabetic patient to program the volume of the bolus dose in accordancewith the size or type of the meal that is consumed by the diabeticpatient. In addition, insulin pumps may also be configured to enable thediabetic patient to infuse a correctional or supplemental bolus dose ofinsulin to compensate for a low blood glucose level at the time when thediabetic patient is calculating the bolus dose for a particular mealthat is to be consumed.

Insulin pumps advantageously deliver insulin over time rather than insingle injections, typically resulting in less variation within theblood glucose range that is recommended. In addition, insulin pumps mayreduce the number of needle sticks which the diabetic patient mustendure, and improve diabetes management to enhance the diabeticpatient's quality of life.

Typically, regardless of whether a diabetic patient uses multiple directinjections (MDIs) or a pump, the diabetic patient takes fasting bloodglucose medication (FBGM) upon awakening from sleep, and also tests forglucose in the blood during or after each meal to determine whether acorrection dose is required. In addition, the diabetic patient may testfor glucose in the blood prior to sleeping to determine whether acorrection dose is required, for instance, after eating a snack beforesleeping.

To facilitate infusion therapy, there are generally two types of insulinpumps, namely, conventional pumps and patch pumps. Conventional pumpsrequire the use of a disposable component, typically referred to as aninfusion set, tubing set or pump set, which conveys the insulin from areservoir within the pump into the skin of the user. The infusion setconsists of a pump connector, a length of tubing, and a hub or base fromwhich a cannula, in the form of a hollow metal infusion needle orflexible plastic catheter extends. The base typically has an adhesivethat retains the base on the skin surface during use. The cannula can beinserted onto the skin manually or with the aid of a manual or automaticinsertion device. The insertion device may be a separate unit requiredby the user.

Another type of insulin pump is a patch pump. Unlike a conventionalinfusion pump and infusion set combination, a patch pump is anintegrated device that combines most or all of the fluidic components,including the fluid reservoir, pumping mechanism and mechanism forautomatically inserting the cannula, in a single housing which isadhesively attached to an infusion site on the patient's skin, and doesnot require the use of a separate infusion or tubing set. A patch pumpcontaining insulin adheres to the skin and delivers the insulin over aperiod of time via an integrated subcutaneous cannula. Some patch pumpsmay wirelessly communicate with a separate controller device (as in onedevice sold by Insulet Corporation under the brand name OmniPod®), whileothers are completely self-contained. Such devices are replaced on afrequent basis, such as every three days, when the insulin reservoir isexhausted or complications may otherwise occur, such as restriction inthe cannula or the infusion site.

As patch pumps are designed to be a self-contained unit that is worn bythe diabetic patient, it is preferable to be as small as possible sothat it does not interfere with the activities of the user. Thus, inorder to minimize discomfort to the user, it would be preferable tominimize the overall thickness of the patch pump. However, in order tominimize the thickness of the patch pump, its constituent parts shouldbe reduced as much as possible. One such part is the insertion mechanismfor automatically inserting the cannula into the user's skin.

In order to minimize the height of the insertion mechanism, someconventional insertion mechanisms are configured to insert the cannulaat an acute angle from the surface of the skin, e.g. 30-45 degrees.However, it may be preferable to insert the cannula perpendicular orclose to the perpendicular from the surface of the skin, since thiswould require the minimum length of cannula insertion. In other words,with the minimum length of cannula being inserted into the user's skin,the user can experience greater comfort and fewer complications, such aspremature kinking of the cannula. But one problem with configuring theinsertion mechanism to insert the cannula perpendicular to the surfaceof the skin is that this may increase the overall height of theinsertion mechanism, and therefore of the patch pump itself.

Accordingly, a need exists for an improved insertion mechanism for usein a limited space environment, such as in the patch pump, that cancost-effectively insert a cannula vertically or close to perpendicularlyinto the surface of a user's skin, while minimizing or reducing itsheight, in order to reduce the overall height of the device theinsertion mechanism is incorporated into, such as a patch pump.

SUMMARY OF THE INVENTION

An object of the present invention is to substantially address the aboveand other concerns, and provide advanced, improved, and novel componentsand elements of an infusion device that facilitates insertion of thein-dwelling or soft catheter and if required, retract the introducerneedle, while reducing the number of components required for theconstruction and use of the infusion device.

Another object of the present invention is to provide an infusion devicethat can utilize components with one or more shared technical featuressuch that each component can serve multiple functions.

Another object of the present invention is to provide an infusion devicethat can utilize components which serve multiple functions, such thatthe part count of the exemplary embodiments is lowered and which servesto keep part production costs low and simplify device assembly.

Another object of the present invention is to provide an infusion devicethat can utilize a cannula spring which functions as an introducerneedle, retraction spring, and fluid path.

Another object of the present invention is to provide an infusion devicethat can utilize an introducer needle, spring, and fluid path as allinherently part of a cannula spring.

These and other objects are substantially achieved by providing aninfusion device with a cannula spring which functions as at least anintroducer needle, spring and fluid path. A single piece of hollowcannula tubing is wound, bent and sharpened into a shape which allows itto operate as an introducer needle, retraction spring and fluid path inan infusion device. A button of the infusion device is used to insertthe introducer needle portion of the cannula spring and a soft catheter,and once the introducer needle portion and catheter have been fullyinserted, an engagement between the button and the base of the infusiondevice releases the cannula spring such that the introducer needleportion of the cannula spring automatically retracts, leaving thecatheter in the body of the user. An end of the introducer needleportion of the cannula spring remains in the inserted catheter toprovide an uninterrupted fluid path.

Additional and/or other aspects and advantages of the present inventionwill be set for in the description that follows, or will be apparentfrom the description, or may be learned by the practice of theinvention. The present invention may comprise a method or apparatus orsystem having one or more of the above aspects, and/or one or more ofthe features and combinations thereof. The present invention maycomprise one or more of the features and/or combinations of the aboveaspects as recited, for example, in the attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The various objects, advantages and novel features of the exemplaryembodiments of the present invention will be more readily appreciatedfrom the following detailed description when read in conjunction withthe appended drawings, in which:

FIG. 1A is a perspective view of an exemplary infusion device prior toactivation in accordance with an embodiment of the present invention;

FIG. 1B is a perspective view of the exemplary infusion device of FIG.1A after activation in accordance with an embodiment of the presentinvention;

FIG. 2 is an enlarged cross-sectional view of the exemplary infusiondevice of FIG. 1A before activation in accordance with an embodiment ofthe present invention;

FIG. 3 is an enlarged cross-sectional view of the exemplary infusiondevice at the beginning of activation in accordance with an embodimentof the present invention;

FIG. 4 is an enlarged cross-sectional view of the exemplary infusiondevice nearing the completion of activation in accordance with anembodiment of the present invention;

FIG. 5 is an enlarged cross-sectional view of the exemplary infusiondevice of FIG. 1B after activation in accordance with an embodiment ofthe present invention;

FIG. 6 is an enlarged perspective view of an exemplary cannula spring ofthe exemplary infusion device in accordance with an embodiment of thepresent invention;

FIG. 7 is a perspective view of a patch pump incorporating a low-profilecannula insertion device, illustrated with a see-through cover forclarity;

FIG. 8 is an exploded view of the various components of the patch pumpof FIG. 7, illustrated with a cover;

FIG. 9 is a perspective view of an alternative design for a patch pumphaving a flexible reservoir, illustrated without a cover; and

FIG. 10 is a patch-pump fluidic architecture and metering sub-systemdiagram of the patch pump of FIG. 9.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components and structures.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The exemplary embodiments of the present invention described belowprovide novel means of providing one or more infusion device elementsthat are configured to share functions, thereby reducing the overallnumber of components required for the construction and use of theinfusion device. In one embodiment, the present invention is directed toan infusion device that provides a cannula spring that is configured tofunction as an introducer needle, retraction spring, and fluidcommunication path, thereby reducing the overall number of componentsrequired for the construction and use of the infusion device.

In an exemplary embodiment, an infusion device utilizes a single pieceof cannula tubing that is wound, bent and sharpened into a shape whichallows it to operate as an introducer needle, retraction spring andfluid path. The cannula spring is configured to operate as an introducerneedle using a sharpened introducer needle portion and operate as aspring using a coiled spring portion. For illustration purposes, thecoiled spring portion in the following discussion is presented as aretraction spring, but is not limited thereto. The retraction springportion works with other components in the set in order to insert theintroducer needle portion along with a catheter into a body of the user.The introducer needle portion is then automatically retracted from thebody using the coiled spring portion and the catheter is left in place.A distal end of the introducer needle portion remains in the insertedcatheter in order to provide an uninterrupted fluid path with thecatheter.

Since the introducer needle, retraction spring and fluid path are allinherently part of the single piece of cannula tubing, no flexibletubing is required. Flexible tubing is used in other designs so thefluid path can move along with the motion of the introducer needleand/or catheter. Such flexible tubing requires significant space withinthe infusion device to keep it from being pinched or kinked. Suchflexible tubing can also be difficult to handle during productionbecause it lacks any rigid shape. Further, since the introducer needle,retraction spring and fluid path are all inherently part of the singlepiece of cannula tubing, the part count of the device is lower and theoverall size of the device is smaller than conventional devices.Accordingly, exemplary embodiments of the present invention keep partproduction costs low, as well as simplify assembly of the infusiondevice.

The exemplary embodiments of the present invention are possible due toone or more shared technical features of the elements therein. Forexample, cannulae of an infusion device are typically constructed usingmetal or plastic, such as 304 stainless steel. In some cases, suchmaterials can also be used to construct springs and fluid paths. Forexample, a diameter of such cannulae can be substantially the same as adiameter of spring wire, such as that used for insertion, retraction, orsafety springs in an infusion device. In one example, an operationalretraction spring can be formed from a single continuous piece of steeltubing with diameter of about 0.0103 inches (0.26 mm), which shares thesame diameter as a 31G steel cannula. 31 G is the most common gauge forsteel in-dwelling patient cannula, such as those available from V-Go™and Orbit™. An exemplary retraction spring formed from the steel tubingwith a diameter of about 0.00103 inches (0.26 mm) in this manner exertsa force of about 0.35 lbs (1.56 N) at the beginning of retraction andabout 0.17 lbs (0.76 N) at the end of the retraction. The spring forceis proportional to the inverse of the polar moment of inertia which, foran annulus, is noted below in Equation (1).π/2(outer radius⁴−inner radius⁴)  Equation (1)

In the above Equation (1), the outer diameter to the fourth power is byfar the dominant term. If a regular wall thickness cannula, that is, acannula with a wall thickness of about 0.003 inches (0.076 mm), is usedto make the retraction spring, the spring force would only drop by about6% compared to the retraction spring formed from the steel tubing with adiameter of about 0.00103 inches (0.26 mm). This reduced spring forcewould still give the necessary retraction force. This indicates that ahollow cannula can be used to construct a retraction spring with thesame geometry, and exhibits very similar behavior. The advantage ofdoing so with an infusion device is that the device then requires fewerparts and would result in a smaller mechanism.

Accordingly, exemplary embodiments of the present invention utilize acannula spring that is made of a single piece of tubing in which one endof the tubing is used as an introducer needle portion and the other endof the tubing is used to connect to a fluid path, and a middle portionof the tubing is coiled to form a spring portion. For discussionpurposes, the spring portion is used as a retraction spring, butembodiments are not limited thereto. In other embodiments, the springportion is used as an insertion spring or safety spring. Further, fordiscussion purposes, a single piece of steel cannula tubing is used, butembodiments are not limited thereto and in other embodiments, plastictubing can be used.

The retraction spring portion works with other components in theinfusion device in order to insert the introducer needle portion alongwith a catheter into the body of the user. The introducer needle portionis then retracted from the body using the retraction spring portion, andthe catheter is left in place. A distal end of the introducer needleportion remains in the inserted catheter in order to provide anuninterrupted fluid path with the catheter.

FIGS. 1A and 1B show an exemplary infusion device in pre-activation andpost-activation states. FIG. 1A is a perspective view of an exemplaryinfusion device prior to activation, and FIG. 1B is a perspective viewof the exemplary infusion device of FIG. 1A after activation inaccordance with an embodiment of the present invention.

In FIGS. 1A and 1B, an infusion device housing 10 is shown having anopening 14 through a top surface from which a user-accessible, anduser-acutatable button 100 slidably extends. As illustrated in FIG. 2,the housing is secured to an infusion device base 200, which includes afirst post 202 and second post 204 to slidably receive the button 100.

The button 100 includes a first projection 102 and a second projection104. The first projection 102 forms an outer surface of the button 100and is slidably received by the first post 202 of the base 200. Thesecond projection 104 extends within the first projection 102 and isslidably received by the second post 204 of the base 200. Each of theposts of the base, and projections of the button, can be substantiallycylindrical but embodiments are not limited thereto. Further, each canbe provided with grooves, slots and openings permitting use of thecannula spring.

The second post 204 of the base 200 slidably contains a septum 226 andtherein a catheter 228 and catheter securing wedge 230 as shown in FIG.3. Catheter 228 is attached to the wedge 230 and the septum 226 isinserted into the wedge 230 and contained in a catheter holder 227. Asdescribed in greater detail below, the second projection 104 of thebutton 100 is used to slidably move the septum 226, catheter 228 andcatheter securing wedge 230 during activation. Other features andfunctions of the infusion device that are well-known to those skilled inthe art are omitted from the figures and discussion for clarity.

The infusion device of FIGS. 1A and 1B is activated by pressing downwardon the button 100 that protrudes from the top of the housing 10. Inorder to ensure that the button 100 is pressed downward with a properforce, speed, smoothness and angle, a set of detents 106, 206 as shownin FIG. 2 are used to keep the button 100 in the up position until theproper activation force, speed, smoothness and angle have been applied.FIG. 2 is an enlarged cross-sectional view of the exemplary infusiondevice of FIG. 1A before activation in accordance with an embodiment ofthe present invention and illustrates detents 106, 206. As shown in FIG.2, the detents 106, 206 include a projecting detent 106 disposed upon anouter circumference of the first projection 102 of the button 100. Therounded, projecting detent 106 is disposed at an end of a deflectablemember 108 of the button 100 and, in an up position, is releasablycaptured by a stepped detent 206 of the first post 202 of the base 200.The projecting detent 106 and thereby, the button 100, is releasablyheld in the up and extended position by the engagement between theprojecting detent 106 and the stepped detent 206.

Once the desired amount of activation force, speed, smoothness and anglehas been applied to the button 100, the detents 106, 206 resilientlydeflect, releasing the engagement between the projecting detent 106 andthe stepped detent 206 allowing the button 100 to be pressed downward asshown in FIG. 3. FIG. 3 is an enlarged cross-sectional view of theexemplary infusion device at the beginning of activation in accordancewith an embodiment of the present invention. Specifically, once thedesired amount of activation force, speed, smoothness and angle has beenapplied to the button 100, the rounded detent 106 and member 108 aredeflected and are released from the engagement with the stepped detent206 of the post 202 of the base 200. The button 100 is then free to bepressed downward against the resistance of the deflected detent 206 andmember 208 resiliently urged into contact with the inner diameter of thepost 202 of the base 200.

The release of the projecting detent 106 from the stepped detent 206 isconfigured to occur once a desired amount of activation force has beenapplied to the button 100. Since the button 100 is releasably held inthe up and extended position by the engagement between the projectingdetent 106 and the stepped detent 206, the force applied to the button100 by the user steadily increases for some period of time prior torelease of the projecting detent 106 from the stepped detent 206. Uponsudden release of the projecting detent 106 from the stepped detent 206,the force has reached a desired value and therefore, the button 100 isaccelerated downward due to the sudden freedom to travel and the desiredforce applied to the button at the time of release and maintainedthereafter. Such release ensures that a desired amount of downwardforce, speed, smoothness and angle has been applied by the user. Suchactivation substantially eliminates variations in the user forceapplied, speed, smoothness and angle thereof, and reduces insertionfailure and/or discomfort to the user.

FIG. 2 also shows an exemplary cannula spring 300 that is made of asingle piece of steel cannula tubing in which one end 302 of the tubingis used as an introducer needle portion and the other end 304 of thetubing is used to connect to a fluid path. A middle portion 306 of thetubing is coiled to form a spring portion. For discussion purposes, thespring portion 306 of the tubing is used as a retraction spring, butembodiments are not limited thereto. In other embodiments, the springportion can be used as an insertion spring or safety spring.

An exemplary path of the cannula spring 300 as shown in FIG. 2 will nowbe described. The end 304 of the cannula spring 300 is used to connectto a fluid path, including any of a reservoir (not shown) within thehousing 10 or to an external reservoir via one or more tube setcouplings (not shown). The end 304 of the cannula spring 300 passesthrough the first post 202 of the base 200, preferably at a portion ator near the interface between the first post 202 and the housing 10 ofthe infusion device. In doing so, the end 304 of the cannula spring 300is used to connect to a fluid path and does not move during theinsertion and retraction process.

The cannula spring 300 is then disposed along a groove or slot 208 inthe first post 202 of the base 200 to avoid interference with the outerdiameter of the button 100, and extends to a position at or near theinterface between the first post 202 and base 200 to avoid interferencewith the lower end of the button 100. The cannula spring 300 is thenextended from the groove or slot 208 in the first post 202, along asurface of the base 200, toward the second post 204.

At the second post 204, the cannula spring 300 is wound to encircle thesecond post 204, thereby forming coils of the retraction spring portion306. Although 4 coils of the retraction spring portion 306 are shown,embodiments of the present invention are not limited thereto. Theretraction spring portion 306 of the cannula spring 300 is disposedaround the second post 204 to a position at or near the top of thesecond post 204. A clearance space is provided between the coils of theretraction spring portion 306 of the cannula spring 300 and an insidediameter of the first projection 102 of the button 100. The cannulaspring 300 is then extended through a groove or slot 210 in the secondpost 204 of the base 200, and extends through a groove or slot 110 ofthe button 100 toward a position above the septum 226.

Once above the septum 226, the cannula spring 300 is angled to extendthrough the septum 226, catheter 228 and catheter securing wedge 230,thereby forming the introducer needle portion 302. The distal end of theintroducer needle portion 302 can be sharpened, beveled or blunt asrequired by the application.

At the point where the cannula spring 300 extends through the slot 110of the button 100, it is releasably captured by a step detent 112 of theslot 110 of the button 100 as shown in FIG. 4. In doing so, as thebutton 100 is pressed downward, the cannula spring 300 passing throughthe button 100 is pressed downward by the step detent 112 of the slot110, thereby activating the coils of the retraction spring portion 306.As described in greater detail below, upon complete activation, thecannula spring 300 is released from the step detent 112 and displacedinto the slot 110 of the button 100, such that the activated coils ofthe retraction spring portion 306 are free to expand through the slot110 of the button 100 and retract the introducer needle portion 302 evenwhile the button 100 is held in the activated position.

FIG. 3 shows the device as the button 100 is just being forced pass thedetents 106 and 206. As noted above, the sudden release of theprojecting detent 106 from the stepped detent 206 is configured to occuronce a desired amount of activation force has been applied to the button100. As the button 100 begins to travel, the second projection 104 ofthe button 100 slidably moves the septum 226, catheter 228 and cathetersecuring wedge 230. It is also at this time when the step detent 112 ofthe button 100 begins to force the cannula spring 300 downward bypushing on the topmost coil of the retraction spring portion 306,thereby simultaneously pushing the introducer needle portion 302downward and activating the coils of the retraction spring portion 306.The sudden release of the projecting detent 106 from the stepped detent206 is configured to allow the button 100 to rapidly and smoothly pushthe introducer needle portion 302 and plastic catheter 228 downward andinto the body of the user with minimal pain and discomfort.

As the button 100 continues to be pressed downward and the introducerneedle portion 302 of the cannula spring 300 reaches the desired depth,the topmost coil of the cannula spring 300 hits an incline or ramp 212in the second post 204 of the base 200 which that forces the cannulaspring 300 to rotate slightly, as indicated in FIG. 4. FIG. 4 is anenlarged cross-sectional view of the exemplary infusion device nearingthe end of activation in accordance with an embodiment of the presentinvention. As the cannula spring 300 rotates, it will no longer be actedupon by the step detent 112 of the button 100, and is released into theslot 110 of the button 100. This allows the activated coils of theretraction spring portion 306 of the cannula spring 300 to expand intothe slot 110 and retract the introducer needle portion 302 from the bodyof the user as shown in FIG. 5.

As noted above, once the desired amount of activation force, speed,smoothness and angle has been applied to the button 100, the roundeddetent 106 and member 108 are deflected and are released from theengagement with the stepped detent 206 of the post 202 of the base 200.The button 100 is then free to be pressed downward against theresistance of the deflected detent 106 and member 108 resiliently urgedinto contact with the inner diameter of the post 202 of the base 200. Ata complete down position, the rounded, projecting detent 106 is capturedwithin a stepped detent 214 of the post 202 of the base 200. Therefore,the projecting detent 106 and thereby, the button 100, is held in thedown and pressed position by the engagement between the projectingdetent 106 and the stepped detent 214 as shown in FIG. 5. Further, theseptum 226, catheter 228 and catheter securing wedge 230 are held in thedown and pressed position by the engagement between the projectingdetent 106 and the stepped detent 214.

FIG. 5 is an enlarged cross-sectional view of the exemplary infusiondevice of FIG. 1B after activation in accordance with an embodiment ofthe present invention. FIG. 5 shows the spring 300 fully expanded, withthe introducer needle portion 302 retracted from the body of the user,wherein the distal end or tip of the introducer needle portion 302 isstill inside the catheter 228, providing a sealed and uninterruptedfluid path.

In the exemplary embodiments, the introducer needle, retraction springand fluid path are all inherently part of the single piece of cannulatubing, and no flexible tubing is required. Flexible tubing is used inother designs so the fluid path can move along with the motion of theintroducer needle and/or catheter. Such flexible tubing requiressignificant space within the infusion device to keep it from beingpinched or kinked. Such flexible tubing can also be difficult to handleduring production because it lacks any rigid shape. Further, since theintroducer needle, retraction spring and fluid path are all inherentlypart of the single piece of cannula tubing, the part count of the deviceis lower and the overall size of the device is smaller than conventionaldevices. Accordingly, exemplary embodiments of the present inventionkeep part production costs low, as well as simplify assembly of theinfusion device.

The cannula spring 300 requires a very small notch or hole in order topass through the water tight seal provided by the walls of the post 202.That is, the post 202 into which water from a shower or swimming is freeto enter through the catheter exit hole or from the button hole in thehousing top, is hermetically sealed with laser welding or gluing,thereby protecting the remaining content of the device housing 10, suchas content of the electronic/pump compartments of the device. The outerwalls of the insertion mechanism also provide a water tight seal. Anynotch or hole can be easily filled with glue around the cannula spring300 in order to provide and maintain the desired water tight seal.

In the exemplary embodiments of the present invention, a single piece ofhollow cannula tubing is wound, bent and sharpened into a shape whichallows it to operate as an introducer needle, retraction spring andfluid path. The button of the infusion device upon activation, is usedto optimally insert the introducer needle portion of the cannula springand a soft catheter, activate the retraction spring portion the cannulaspring, and once the introducer needle portion and catheter have beenfully inserted, release the retraction spring portion the cannula springsuch that the introducer needle portion automatically retracts, leavingthe catheter in the body of the user. An end of the introducer needleportion of the cannula spring remains in the inserted catheter toprovide an uninterrupted fluid path.

The exemplary embodiments of the present invention are possible due toone or more shared technical features of the elements therein.Accordingly, an object of the present invention is to provide a cannulaspring which functions as an introducer needle, spring, and fluid path.An example of such a cannula spring 300 as described in regard to FIGS.1-5, is shown in FIG. 6. FIG. 6 is an enlarged perspective view of anexemplary cannula spring in accordance with an embodiment of the presentinvention.

In regard to FIG. 6, the cannula spring 300 is shown removed from thedevice to show the end 302 of the tubing used as an introducer needleportion and the other end 304 used to connect to a fluid path, and amiddle portion 306 coiled to form a spring portion. In the embodimentshown in FIG. 6, the long tail of the cannula spring 300 can be bent inany desired shape or contour to mate with any of a reservoir, pump orother supply. A diameter of the cannulae spring 300 can be substantiallythe same as the diameter required for an introducer needle, and can besubstantially the same as the diameter required for spring wire. Wherecannulae of an infusion device are constructed using metal or plastic,such as 304 stainless steel, such materials can also be used toconstruct springs and fluid paths. A diameter of such cannulae can besubstantially the same as a diameter of spring wire, such as that usedfor insertion, retraction, or safety springs in an infusion device. Theexemplary cannula spring 300 can be formed from a single continuouspiece of steel tubing with diameter of about 0.0103 inches (0.26 mm),which shares the same diameter as a 31G steel cannula. 31 G is the mostcommon gauge for steel in-dwelling patient cannula, such as thoseavailable from V-Go™ and Orbit™. The exemplary cannula spring 300 formedfrom the steel tubing with diameter of about 0.0103 inches (0.26 mm) inthis manner exerts a force of about 0.35 lbs (1.56 N) at the beginningof retraction and about 0.17 lbs (0.76 N) at the end of the retraction.The spring force is proportional to the inverse of the polar moment ofinertia which, for an annulus, is noted below in Equation (1), repeatedbelow.π/2(outer radius⁴−inner radius⁴)  Equation (1)

If a regular wall thickness cannula, that is, a cannula with a wallthickness of about 0.003 inches (0.076 mm), is used to make theexemplary cannula spring 300, the spring force would only drop by about6% compared to the retraction spring formed from the steel tubing with adiameter of about 0.00103 inches (0.26 mm). This reduced spring forcewould still give the necessary retraction force. Accordingly, an fluidinfusion device can be provided with a cannula spring which functions asan introducer needle, a retraction return spring, and a fluid path, thatfacilitates insertion of the in-dwelling or soft catheter and ifrequired, retract the introducer needle, while reducing the number ofcomponents required for the construction and use of the infusion device.

In the above embodiments, a patch pump can be provided with one or moreof the described features. FIG. 7 is a perspective view of an exemplaryembodiment of a patch pump 1 according to an exemplary embodiment of theinvention. The patch pump 1 is illustrated with a see-through cover forclarity and illustrates various components that are assembled to formthe patch pump 1. FIG. 8 is an exploded view of the various componentsof the patch pump of FIG. 7, illustrated with a solid cover 2. Thevarious components of the patch pump 1 may include: a reservoir 4 forstoring fluid such as insulin; a pump 3 for pumping insulin out of thereservoir 4; a power source 5 in the form of one or more batteries; aninsertion mechanism 7 for inserting an inserter needle with a catheterinto a user's skin; control electronics 8 in the form of a circuit boardwith optional communications capabilities to outside devices such as aremote controller and computer, including a smart phone; a dose button 6on the cover 2 for actuating an insulin dose, including a bolus dose;and a base 9 to which various components above may be attached viafasteners 91. The patch pump 1 also includes various fluid connectorlines that transfer insulin pumped out of the reservoir 4 to theinfusion site.

As noted above, it should be understood that inserter mechanisms come invarious configurations. In some embodiments, the inserter mechanisminserts a soft catheter into the skin. In these embodiments, typicallythe soft catheter is supported on a rigid insertion needle. Theinsertion needle is inserted into the skin along with the soft catheter,and then retracted from the skin, leaving the soft catheter in the skin.In other embodiments, a soft catheter is not provided, and the insertionneedle remains in the skin and forms a portion of the fluid flow path todeliver fluid until the infusion is finished. For discussion purposes,the fluid is an insulin fluid, but embodiments are not limited thereto.Insertion needles are typically hollow, and need to be hollow if theyform part of the insulin flow path. However, insertion needles thatsupport a soft catheter and then retract may be solid or hollow. If theinsertion needle deploys a soft catheter, and retracts but remains partof the insulin flow path, then the insertion needle should be hollow.However, if the insertion needle deploys a soft catheter and thenretracts but does not form part of the insulin flow path, then theinsertion needle may be solid or hollow. In either case, the insertionneedle is preferably rigid enough to reliably penetrate the skin, butotherwise may be made flexible enough to provide comfort to the user.

FIG. 9 is a perspective view of an alternative design for a patch pump1A having a flexible reservoir 4A, and illustrated without a cover. Sucharrangement may further reduce the external dimensions of the patch pump1A, with the flexible reservoir 4A filling voids within the patch pump1A. The patch pump 1A is illustrated with a conventional cannulainsertion device 7A that inserts the cannula, typically at an acuteangle, less than 90 degrees, at the surface of a user's skin. The patchpump 1A further comprises: a power source 5A in the form of batteries; ametering sub-system 41 that monitors the volume of insulin and includesa low volume detecting ability; control electronics 8A for controllingthe components of the device; and a reservoir fill port 43 for receivinga refill syringe 45 to fill the reservoir 4A.

FIG. 10 is a patch-pump fluidic architecture and metering sub-systemdiagram of the patch pump 1A of FIG. 9. The power storage sub-system forthe patch pump 1A includes batteries 5A. The control electronics 8A ofthe patch pump 1A may include a microcontroller 81, sensing electronics82, pump and valve controller 83, sensing electronics 85, and deploymentelectronics 87 that control the actuation of the patch pump 1A. Thepatch pump 1A includes a fluidics sub-system that may include areservoir 4A, volume sensor 48 for the reservoir 4A, a reservoir fillport 43 for receiving a refill syringe 45 to refill the reservoir 4A.The fluidics sub-system may include a metering system comprising a pumpand valve actuator 411 and an integrated pump and valve mechanism 413.The fluidics sub-system may further include an occlusion sensor, adeploy actuator, as well as the cannula 47 for insertion into aninfusion site on the user's skin. The architecture for the patch pumpsof FIGS. 7 and 8 is the same or similar to that which is illustrated inFIG. 10.

Although only a few exemplary embodiments of the present invention havebeen described in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of the appended claims andtheir equivalents.

The invention claimed is:
 1. An fluid infusion device, comprising: a body, comprising an activation button; a base, slidably receiving said activation button; and a hollow cannula tubing member comprising an introducer needle portion and a spring portion wherein the introducer needle portion and the spring portion are integrally formed, wherein said activation button is slidable to insert said introducer needle portion of said hollow cannula tubing member into a body of a user and activate said spring portion of said hollow cannula tubing member, and upon insertion, release said spring portion of said hollow cannula tubing member to retract said introducer needle portion of said hollow cannula tubing member from said body of said user; further comprising: a catheter for insertion by said introducer needle portion of said hollow cannula tubing member into said body of said user, wherein an end of said introducer needle portion of said hollow cannula tubing member remains in fluid communication with said catheter in said body of said user to comprise an uninterrupted fluid path.
 2. The fluid infusion device of claim 1, wherein said hollow cannula tubing member further comprises a fluid path portion.
 3. The fluid infusion device of claim 1, further comprising: a detent disposed on said activation button to releasably engage said base, wherein said detent is configured to secure said button in a first position until an activation force applied to said button exceeds a threshold.
 4. The fluid infusion device of claim 1, further comprising: a detent disposed on said activation button to releasably engage said base, wherein said detent is configured to secure said button in a second position after an activation force has been applied to said button.
 5. An fluid infusion device, having a body and an activation button, and a base slidably receiving said activation button, comprising: a hollow cannula tubing member comprising an introducer needle portion and a spring portion, wherein the introducer needle portion and the spring portion are integrally formed, wherein said introducer needle portion of said hollow cannula tubing member is moveable in a first direction as said spring portion of said hollow cannula tubing member is activated, and said spring portion of said hollow cannula tubing member is expandable to move said introducer needle portion of said tubing in a second direction as said spring portion of said hollow cannula tubing member is expanded; wherein said hollow cannula tubing member remains in fluid communication with a catheter inserted into the body of a user by the introducer needle portion.
 6. The fluid infusion device of claim 5, wherein said hollow cannula tubing member further comprises a fluid path portion.
 7. An fluid infusion device, having a body and an activation button, and a base slidably receiving said activation button, comprising: a hollow cannula tubing member comprising an introducer needle portion and a spring portion, wherein the introducer needle portion and the spring portion are integrally formed, wherein said introducer needle portion of said hollow cannula tubing member is moveable in a first direction as said spring portion of said hollow cannula tubing member is activated, and said spring portion of said hollow cannula tubing member is expandable to move said introducer needle portion of said hollow cannula tubing member in a second direction as said spring portion of said hollow cannula tubing member is expanded; and a catheter disposed upon said introducer needle portion of said hollow cannula tubing member for insertion by said introducer needle portion of said hollow cannula tubing member into a body of a user.
 8. The fluid infusion device of claim 7, wherein an end of said introducer needle portion of said hollow cannula tubing member remains in fluid communication with said catheter in said body of said user to comprise an uninterrupted fluid path.
 9. The fluid infusion device of claim 7, wherein said hollow cannula tubing member further comprises a fluid path portion. 